Mainz ended their association with El Ghazi earlier this month over a social media post regarding the Israel-Palestine conflict.
El Ghazi was initially suspended by Mainz on October 17 after putting out a pro-Palestine statement on his social media handles.
Mainz had a meeting with El Ghazi and wanted him to apologise for the post but he instead wished for peace in the ongoing conflict.
"I don't see any statement in the latest post that is not covered by freedom of expression," the winger's lawyer told Allgemeine Zeitung.
A trial for the case will take place on December 6.
The 28-year-old only joined Mainz as a free agent in September after leaving PSV Eindhoven and played three times for the German side.
El Ghazi has previously spent time in the Premier League with Aston Villa and Everton.
He has won two caps for the Netherlands national team.
